Wednesday, November 29, 2017

Brighten Your Space with Indoor Citrus By Olivia Tracy

Etrog Citron (Citrus medica); photo courtesy of Olivia Tracy

This winter, if you’re hoping to cheer up your indoor space, why not incorporate the bright color and invigorating scent of a citrus tree? While some citrus varieties are too large to grow indoors, there are dwarf cultivars of lime, lemon, orange and tangerine that can grow in containers, including the ancient Etrog Citron (Citrus medica; pictured); sour citrus does particularly well, as it requires less heat to ripen.3 While many nurseries are now closed for the season, you can still mail-order dwarf citrus trees from reputable seed and plant distributors. 

Some Indoor Citrus Varieties Include:1,2,3 
Bearss Lime (Citrus latifolia)
Kaffir Lime (Citrus hystrix), grown mostly for the leaves

Meyer lemon (Citrus x meyeri)
Variegated Pink Lemon (Citrus x limon)

Mandarin/Satsuma Oranges (Citrus reticulata); actually a tangerine, with fragrant flowers and the familiar ‘orange.’
Calamondin Orange (Citrofortunella mitis), a small, sour orange; often grown as an ornamental.

Citrus Tree Care: 
  • Whether you select a lime, lemon, or tangerine tree, citrus trees prefer slightly acidic, well-drained soils, ideally with a pH between 6 and 7. For fertilizer, an all-purpose or acid-loving fertilizer with a 2-1-1 formulation should provide the extra nitrogen that citrus trees need.1,3
  • These trees also require at least six hours a day of sunlight, and do best near south or southwest facing windows; you can use a grow-light if your tree isn’t getting more than six hours of sun. To flower, they also need average daytime temperatures of 65 degrees; the temperature should cool by five to ten degrees overnight.1,2 
  • Water the plants once every five to seven days, and allow the soil at the surface to completely dry between waterings; citrus trees can generally survive a dry spell, but, like many houseplants, they will begin to decline if their roots are suffocated by too much water. They do enjoy humidity, which can be produced by placing a shallow tray of water near the tree, or by misting the tree with rainwater daily.1 
  • If you’re trying to produce fruit indoors over the winter, you’ll need to flick flowers slightly to help them self-pollinate, or they won’t be able to produce fruit.2
With careful selection, and attention to sunlight, temperature, water and humidity, you should be able to keep your citrus tree happy through the winter. 

Information in this post was adapted from the following resources, which are excellent sources for further reading:
1“Growing Citrus Indoors,” El Paso County CSU Extension Office

2 “Growing Citrus Indoors in Minnesota,” University of Minnesota Extension

3“Indoor Citrus,” Master Gardener Program, University of Wisconsin Extension